diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/clk.txt | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/Documentation/clk.txt b/Documentation/clk.txt index be909ed45970..511628bb3d3a 100644 --- a/Documentation/clk.txt +++ b/Documentation/clk.txt @@ -268,9 +268,19 @@ The common clock framework uses two global locks, the prepare lock and the enable lock. The enable lock is a spinlock and is held across calls to the .enable, -.disable and .is_enabled operations. Those operations are thus not allowed to -sleep, and calls to the clk_enable(), clk_disable() and clk_is_enabled() API -functions are allowed in atomic context. +.disable operations. Those operations are thus not allowed to sleep, +and calls to the clk_enable(), clk_disable() API functions are allowed in +atomic context. + +For clk_is_enabled() API, it is also designed to be allowed to be used in +atomic context. However, it doesn't really make any sense to hold the enable +lock in core, unless you want to do something else with the information of +the enable state with that lock held. Otherwise, seeing if a clk is enabled is +a one-shot read of the enabled state, which could just as easily change after +the function returns because the lock is released. Thus the user of this API +needs to handle synchronizing the read of the state with whatever they're +using it for to make sure that the enable state doesn't change during that +time. The prepare lock is a mutex and is held across calls to all other operations. All those operations are allowed to sleep, and calls to the corresponding API |